Civilization has been highly influenced by the emergence of very efficient structural materials (materials possessing a high strength/weight ratio). Mankind's ability to feed, clothe, shelter, transport, educate and provide adequate medical care for itself can be shown to be directly linked with structures possessing high structural efficiency.
Engineers, in their effort to design structures with superior strength/weight ratios, have relied increasingly on "sandwich" configurations consisting of low density core materials with high strength face sheets. The aircraft industry is an excellent example of where light weight, high strength structures are routinely designed. It is not uncommon for the aircraft industry to select "honeycomb" type materials as the core material. Commercially available honeycomb core materials in use today are made of bonded web materials. The web materials are either metallic foils or fiber/matrix composites.
Two existing methods for producing honeycomb structural materials are (a) the hobe method, which is the cardboard box technique of laying up layers of web material with offset stripes of glue, followed by using a jack to pull the layers apart; and (b) the corrugating method, which consists of producing corrugated sheets, registering (matching up) the nodes or the tips of the flutes, and then adhering them by spot gluing, welding or the like. The present invention is an improvement on the latter approach.
The prior art technique of corrugating sheets and then forming a core material from two or more of these sheets is illustrated in a number of U.S. Pat. for example No. 3,700,518; No. 4,935,082; and No. 4,948,445. The assembling technique involved in this method suffers from some recognized difficulties. For example, in order to join the nodes or flute tips of adjacent corrugated sheets, it is necessary for the operator to register the matching nodes by hand and eye and then use special pains to insure that, once registered correctly, the layers will not creep or slip before the adhesive sets. Also, the minimum bonding area involved in spot adhering provides a weak point in the overall strength of the core. Further, the sharp creases normally found in conventional corrugation core nodes contribute an additional weakness in the overall core strength.
It is an object of the invention to provide a honeycomb core material which substantially overcomes the several problems referred to above.
It is another object of the invention to provide honeycomb core components which have inherent indexing or nesting features permitting automatic registration of the matching nodes of adjacent components.
It is a further object to provide core components which provide greater bonding areas between adjacent components and avoid the creases of conventional corrugation techniques, whereby the strength of the core is substantially increased.
It is a further object of the invention to provide for reinforcing integral columns that will greatly add to the compression carrying capacity of the material.
It is a still further object to provide a method for producing core components, wherein the basic raw materials are processed in a continuous integrated procedure adaptable for a fully automated production system.
Other objects and advantages of the invention will become apparent as the specification proceeds.